chore(memory): BLK-021/022, LRN-150/151, BDR-088, EVAL-029 — macOS port

Capitalizes the macOS port and the gstack Chromium deadlock, plus an
append-only correction to BLK-008 / LRN-038: their "ubuntu24.04 fallback
build" cause is refuted — macOS arm64 has a native Playwright 1.58.2 build,
no fallback, and the same hang reproduces. The real variable was the Node
version, and that wrong record misdirected this investigation for an hour.

EVAL-029 records two process failures worth keeping: the first fix
recommendation (pin node@22) was reversed only because the user asked
whether the browser was current — staleness had gone unpriced; and the grep
sweep returned empty twice while defects were present, once to `set -e`,
once to a pattern that could not match `${1,,}`.

Index rows added for all four registries. Pre-existing index drift
(BLK-018..020, LRN-144..149) left alone — backfilling means summarising
entries someone else wrote.

.claude/memory/decisions.md

@@ -97,6 +97,7 @@ rules:
 | BDR-085 | 2026-08-25 | User permanent rules: writing-style always-on in rules/, web build+security path-scoped | accepted |
 | BDR-086 | 2026-08-26 | darwin: threshold gates full loops; verified defects fixed regardless of unit score (paired-validated, batched checkpoint) | accepted |
 | BDR-087 | 2026-09-03 | Stop hook = attention signal only, never control flow; one script for Notification + Stop | accepted |
+| BDR-088 | 2026-09-13 | gstack browser: guarded pre-install (900s deadline + Playwright bump-retry), not a pinned Node | accepted |
 
 ---
 
@@ -1123,3 +1124,11 @@ Branch feature/user-writing-web-rules, UNMERGED (human gate).
 - **Guard vs prior refusal**: [[BDR-083]] (unlazy review, GATE 0) REFUSED a Stop hook using `decision:"block"` (forces continuation, inverts human gates). THIS Stop hook returns `terminalSequence` + `suppressOutput` only, exit 0, zero control-flow effect. Signal ≠ control. Do not read the refusal as banning Stop outright.
 - **Status**: accepted.
 - **Reference**: [[LRN-146]] event-coverage gap, [[BLK-020]] client-side faults, [[LRN-145]] terminalSequence pattern. Verified live: turn-end + AskUserQuestion both ring; `permission_prompt` unexercisable under `defaultMode: auto`.
+
+## BDR-088 — gstack browser: guarded pre-install (deadline + bump-retry), not a pinned Node
+- **Date**: 2026-09-13
+- **Decision**: `install-plugins.sh` pre-installs gstack's Chromium BEFORE `./setup`, wrapped in a portable timeout (`_run_with_timeout`, `GSTACK_BROWSER_TIMEOUT=900`). On deadline: `bun add playwright@latest` in the submodule, retry once, then WARN (non-fatal — gstack is OFF by default; only `/browse`, `/qa` and screenshots depend on it). New helpers: `_run_with_timeout` (pure bash — coreutils `timeout` is absent from a stock macOS), `_gstack_bun_install` (extracted, shared with `gstack_bump_playwright_if_unsupported`), `_gstack_pw_install`.
+- **Why**: REACT to the observed failure (a hang) instead of PREDICTING it — no version table to maintain, and it self-heals for future Node x Playwright pairs. The deadline alone fixes the worst defect: an installer that hangs forever with no message (it silently cut step 2/10 here, and forced a Ctrl+C on Ubuntu per [[BLK-008]]).
+- **Alternatives rejected**: pin `node@22` for gstack's setup (freezes Chrome at 145, EIGHT majors behind stable 153, adds a node@22 dep, and only masks the symptom — this was the FIRST recommendation, reversed once the browser-staleness was priced, see [[EVAL-029]]); widen `gstack_bump_playwright_if_unsupported`'s `/etc/os-release` gate with a Node-version table (brittle: `engines` declares no upper bound, so there is nothing authoritative to compare); document only (a clean cache re-hangs with no signal).
+- **Status**: accepted.
+- **Reference**: `install-plugins.sh` `_run_with_timeout` / `gstack_install_browser_guarded`. Guard proven by FORCED failure (hang → rc 124 in 6s, no orphaned `oopDownloadBrowserMain`, stderr clean after fd-park) and by a real run (browser present → `ok` in 5s, idempotent). [[BLK-021]], [[LRN-150]].